System for thin film deposition utilizing compensating forces

ABSTRACT

A process for depositing a thin film material on a substrate is disclosed, comprising simultaneously directing a series of gas flows from the output face of a delivery head of a thin film deposition system toward the surface of a substrate, and wherein the series of gas flows comprises at least a first reactive gaseous material, an inert purge gas, and a second reactive gaseous material, wherein the first reactive gaseous material is capable of reacting with a substrate surface treated with the second reactive gaseous material. A system capable of carrying out such a process is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. application Ser. No.11/392,007, filed Mar. 29, 2006 by Levy and entitled, “PROCESS FORATOMIC LAYER DEPOSITION,” U.S. application Ser. No. 11/392,006, filedMar. 29, 2006 by Levy and entitled “APPARATUS FOR ATOMIC LAYERDEPOSITION,” U.S. application Ser. No. 11/620,738, filed Jan. 8, 2007,by Levy and entitled “DELIVERY DEVICE FOR DEPOSITION,” U.S. applicationSer. No. 11/620,740, filed Jan. 8, 2007 by Nelson et al. and entitled“DELIVERY DEVICE COMPRISING GAS DIFFUSER FOR THIN FILM DEPOSITION,” U.S.application Ser. No. 11/620,744, filed Jan. 8, 2007 by Levy andentitled, “DEPOSITION SYSTEM AND METHOD USING A DELIVERY HEAD SEPARATEDFROM A SUBSTRATE BY GAS PRESSURE,” U.S. application Ser. No. 11/861,420filed Sep. 26, 2007 by Kerr et al. and entitled, “DEPOSITION SYSTEM FORTHIN FILM FORMATION,” U.S. application Ser. No. 11/861,402 filed Sep.26, 2007 by Kerr et al. and entitled “DELIVERY DEVICE COMPRISING FORDEPOSITION,” and U.S. application Ser. No. 11/861,359 filed Sep. 26,2007 by Levy et al. and entitled, “DEPOSITION SYSTEM FOR THIN FILMFORMATION” all the above identified applications incorporated byreference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to the deposition of thin-filmmaterials and, more particularly, to an apparatus and method for atomiclayer deposition onto a substrate using a distribution head directingsimultaneous gas flows onto a substrate.

BACKGROUND OF THE INVENTION

Among the techniques widely used for thin-film deposition is ChemicalVapor Deposition (CVD) that uses chemically reactive molecules thatreact in a reaction chamber to deposit a desired film on a substrate.Molecular precursors useful for CVD applications comprise elemental(atomic) constituents of the film to be deposited and typically alsoinclude additional elements. CVD precursors are volatile molecules thatare delivered, in a gaseous phase, to a chamber in order to react at thesubstrate, forming the thin film thereon. The chemical reaction depositsa thin film with a desired film thickness.

Common to most CVD techniques is the need for application of awell-controlled flux of one or more molecular precursors into the CVDreactor. A substrate is kept at a well-controlled temperature undercontrolled pressure conditions to promote chemical reaction betweenthese molecular precursors, concurrent with efficient removal ofbyproducts. Obtaining optimum CVD performance requires the ability toachieve and sustain steady-state conditions of gas flow, temperature,and pressure throughout the process, and the ability to minimize oreliminate transients.

Especially in the field of semiconductor, integrated circuit, and otherelectronic devices, there is a demand for thin films, especially higherquality, denser films, with superior conformal coating properties,beyond the achievable limits of conventional CVD techniques, especiallythin films that can be manufactured at lower temperatures.

Atomic layer deposition (“ALD”) is an alternative film depositiontechnology that can provide improved thickness resolution and conformalcapabilities, compared to its CVD predecessor. The ALD process segmentsthe conventional thin-film deposition process of conventional CVD intosingle atomic-layer deposition steps. Advantageously, ALD steps areself-terminating and can deposit one atomic layer when conducted up toor beyond self-termination exposure times. An atomic layer typicallyranges from about 0.1 to about 0.5 molecular monolayers, with typicaldimensions on the order of no more than a few Angstroms. In ALD,deposition of an atomic layer is the outcome of a chemical reactionbetween a reactive molecular precursor and the substrate. In eachseparate ALD reaction-deposition step, the net reaction deposits thedesired atomic layer and substantially eliminates “extra” atomsoriginally included in the molecular precursor. In its most pure form,ALD involves the adsorption and reaction of each of the precursors inthe absence of the other precursor or precursors of the reaction. Inpractice, in any system it is difficult to avoid some direct reaction ofthe different precursors leading to a small amount of chemical vapordeposition reaction. The goal of any system claiming to perform ALD isto obtain device performance and attributes commensurate with an ALDsystem while recognizing that a small amount of CVD reaction can betolerated.

In ALD applications, typically two molecular precursors are introducedinto the ALD reactor in separate stages. For example, a metal precursormolecule, ML_(x), comprises a metal element, M that is bonded to anatomic or molecular ligand, L. For example, M could be, but would not berestricted to, Al, W, Ta, Si, Zn, etc. The metal precursor reacts withthe substrate when the substrate surface is prepared to react directlywith the molecular precursor. For example, the substrate surfacetypically is prepared to include hydrogen-containing ligands, AH or thelike, that are reactive with the metal precursor. Sulfur (S), oxygen(O), and Nitrogen (N) are some typical A species. The gaseous metalprecursor molecule effectively reacts with all of the ligands on thesubstrate surface, resulting in deposition of a single atomic layer ofthe metal:substrate−AH+ML_(x)→substrate−AML_(x-1)+HL  (1)where HL is a reaction by-product. During the reaction, the initialsurface ligands, AH, are consumed, and the surface becomes covered withL ligands, which cannot further react with metal precursor ML_(x).Therefore, the reaction self-terminates when all of the initial AHligands on the surface are replaced with AML_(x-1) species. The reactionstage is typically followed by an inert-gas purge stage that eliminatesthe excess metal precursor from the chamber prior to the separateintroduction of a second reactant gaseous precursor material.

The second molecular precursor then is used to restore the surfacereactivity of the substrate towards the metal precursor. This is done,for example, by removing the L ligands and redepositing AH ligands. Inthis case, the second precursor typically comprises the desired (usuallynonmetallic) element A (i.e., O, N, S), and hydrogen (i.e., H₂O, NH₃,H₂S). The next reaction is as follows:substrate−A−ML+AH_(Y)→substrate−A−M−AH+HL  (2)This converts the surface back to its AH-covered state. (Here, for thesake of simplicity, the chemical reactions are not balanced.) Thedesired additional element, A, is incorporated into the film and theundesired ligands, L, are eliminated as volatile by-products. Onceagain, the reaction consumes the reactive sites (this time, the Lterminated sites) and self-terminates when the reactive sites on thesubstrate are entirely depleted. The second molecular precursor then isremoved from the deposition chamber by flowing inert purge-gas in asecond purge stage.

In summary, then, the basic ALD process requires alternating, insequence, the flux of chemicals to the substrate. The representative ALDprocess, as discussed above, is a cycle having four differentoperational stages:

-   1. ML_(x) reaction;-   2. ML_(x) purge;-   3. AH_(y) reaction; and-   4. AH_(y) purge, and then back to stage 1.

ALD has been typically utilized for the deposition of inorganiccompounds where metal precursors have been halides, alkoxides,-diketonate chelates or organometallic compounds. The second precursorhas been typically an oxygen, nitrogen or sulfur source, when oxides,nitrides, or sulfides are deposited, respectively. Although it has beenless studied, the deposition of organic compounds or organic/inorganichybrid layers by ALD is possible. In these cases, it is possible tostill have an alternating sequence of self-limiting reactions, exceptthat the limiting layer produced by such a process may be a layer ofmolecules as opposed to atoms. As such, such techniques may also bereferred to as molecular layer deposition (MLD), although the basicconcepts and deposition equipment are similar to ALD processes andequipment. An example of atomic layer or molecular layer deposition oforganic films can be found in “Atomic layer deposition of polyimide thinfilms,” by Matti Putkonen, et. al. in The Journal of MaterialsChemistry, 2007, (7), 664-669.

This repeated sequence of alternating surface reactions andprecursor-removal that restores the substrate surface to its initialreactive state, with intervening purge operations, is a typical ALDdeposition cycle. A key feature of ALD operation is the restoration ofthe substrate to its initial surface chemistry condition. Using thisrepeated set of steps, a film can be layered onto the substrate in equalmetered layers that are all alike in chemical kinetics, deposition percycle, composition, and thickness.

ALD can be used as a fabrication step for forming a number of types ofthin-film electronic devices, including semiconductor devices andsupporting electronic components such as resistors and capacitors,insulators, bus lines, and other conductive structures. ALD isparticularly suited for forming thin layers of metal oxides in thecomponents of electronic devices. General classes of functionalmaterials that can be deposited with ALD include conductors, dielectricsor insulators, and semiconductors.

Conductors can be any useful conductive material. For example, theconductors may comprise transparent materials such as indium-tin oxide(ITO), doped zinc oxide ZnO, SnO₂, or In₂O₃. The thickness of theconductor may vary, and according to particular examples it can rangefrom about 50 to about 1000 nm.

Examples of useful semiconducting materials are compound semiconductorssuch as gallium arsenide, gallium nitride, cadmium sulfide, intrinsiczinc oxide, and zinc sulfide.

A dielectric material electrically insulates various portions of apatterned circuit. A dielectric layer may also be referred to as aninsulator or insulating layer. Specific examples of materials useful asdielectrics include strontiates, tantalates, titanates, zirconates,aluminum oxides, silicon oxides, tantalum oxides, hafnium oxides,titanium oxides, zinc selenide, and zinc sulfide. In addition, alloys,combinations, and multilayers of these examples can be used asdielectrics. Of these materials, aluminum oxides are preferred.

A dielectric structure layer may comprise two or more layers havingdifferent dielectric constants. Such insulators are discussed in U.S.Pat. No. 5,981,970 hereby incorporated by reference and copending USPublication No. 2006/0214154, hereby incorporated by reference.Dielectric materials typically exhibit a band-gap of greater than about5 eV. The thickness of a useful dielectric layer may vary, and accordingto particular examples it can range from about 10 to about 300 nm.

A number of device structures can be made with the functional layersdescribed above. A resistor can be fabricated by selecting a conductingmaterial with moderate to poor conductivity. A capacitor can be made byplacing a dielectric between two conductors. A diode can be made byplacing two semiconductors of complementary carrier type between twoconducting electrodes. There may also be disposed between thesemiconductors of complementary carrier type a semiconductor region thatis intrinsic, indicating that that region has low numbers of free chargecarriers. A diode may also be constructed by placing a singlesemiconductor between two conductors, where one of theconductor/semiconductors interfaces produces a Schottky barrier thatimpedes current flow strongly in one direction. A transistor may be madeby placing upon a conductor (the gate) an insulating layer followed by asemiconducting layer. If two or more additional conductor electrodes(source and drain) are placed spaced apart in contact with the topsemiconductor layer, a transistor can be formed. Any of the abovedevices can be created in various configurations as long as thenecessary interfaces are created.

In typical applications of a thin film transistor, the need is for aswitch that can control the flow of current through the device. As such,it is desired that when the switch is turned on, a high current can flowthrough the device. The extent of current flow is related to thesemiconductor charge carrier mobility. When the device is turned off, itis desirable that the current flow be very small. This is related to thecharge carrier concentration. Furthermore, it is generally preferablethat visible light have little or no influence on thin-film transistorresponse. In order for this to be true, the semiconductor band gap mustbe sufficiently large (>3 eV) so that exposure to visible light does notcause an inter-band transition. A material that is capable of yielding ahigh mobility, low carrier concentration, and high band gap is ZnO.Furthermore, for high-volume manufacture onto a moving web, it is highlydesirable that chemistries used in the process be both inexpensive andof low toxicity, which can be satisfied by the use of ZnO and themajority of its precursors.

Self-saturating surface reactions make ALD relatively insensitive totransport non-uniformities, which might otherwise impair surfaceuniformity, due to engineering tolerances and the limitations of theflow system or related to surface topography (that is, deposition intothree dimensional, high aspect ratio structures). As a general rule, anon-uniform flux of chemicals in a reactive process generally results indifferent completion times over different portions of the surface area.However, with ALD, each of the reactions is allowed to complete on theentire substrate surface. Thus, differences in completion kineticsimpose no penalty on uniformity. This is because the areas that arefirst to complete the reaction self-terminate the reaction; other areasare able to continue until the full treated surface undergoes theintended reaction.

Typically, an ALD process deposits about 0.1-0.2 nm of a film in asingle ALD cycle (with one cycle having numbered steps 1 through 4 aslisted earlier). A useful and economically feasible cycle time must beachieved in order to provide a uniform film thickness in a range of fromabout 3 nm to 30 nm for many or most semiconductor applications, andeven thicker films for other applications. According to industrythroughput standards, substrates are preferably processed within 2minutes to 3 minutes, which means that ALD cycle times must be in arange from about 0.6 seconds to about 6 seconds.

ALD offers considerable promise for providing a controlled level ofhighly uniform thin film deposition. However, in spite of its inherenttechnical capabilities and advantages, a number of technical hurdlesstill remain. One important consideration relates to the number ofcycles needed. Because of its repeated reactant and purge cycles,effective use of ALD has required an apparatus that is capable ofabruptly changing the flux of chemicals from ML_(x) to AH_(y), alongwith quickly performing purge cycles. Conventional ALD systems aredesigned to rapidly cycle the different gaseous substances onto thesubstrate in the needed sequence. However, it is difficult to obtain areliable scheme for introducing the needed series of gaseousformulations into a chamber at the needed speeds and without someunwanted mixing. Furthermore, an ALD apparatus must be able to executethis rapid sequencing efficiently and reliably for many cycles in orderto allow cost-effective coating of many substrates.

In an effort to minimize the time that an ALD reaction needs to reachself-termination, at any given reaction temperature, one approach hasbeen to maximize the flux of chemicals flowing into the ALD reactor,using so-called “pulsing” systems. In order to maximize the flux ofchemicals into the ALD reactor, it is advantageous to introduce themolecular precursors into the ALD reactor with minimum dilution of inertgas and at high pressures. However, these measures work against the needto achieve short cycle times and the rapid removal of these molecularprecursors from the ALD reactor. Rapid removal in turn dictates that gasresidence time in the ALD reactor be minimized. Gas residence times, τ,are proportional to the volume of the reactor, V, the pressure, P, inthe ALD reactor, and the inverse of the flow, Q, that is:τ=VP/Q  (3)

In a typical ALD chamber, the volume (V) and pressure (P) are dictatedindependently by the mechanical and pumping constraints, leading todifficulty in precisely controlling the residence time to low values.Accordingly, lowering pressure (P) in the ALD reactor facilitates lowgas residence times and increases the speed of removal (purge) ofchemical precursor from the ALD reactor. In contrast, minimizing the ALDreaction time requires maximizing the flux of chemical precursors intothe ALD reactor through the use of a high pressure within the ALDreactor. In addition, both gas residence time and chemical usageefficiency are inversely proportional to the flow. Thus, while loweringflow can increase efficiency, it also increases gas residence time.

Existing ALD approaches have been compromised with the trade-off betweenthe need to shorten reaction times with improved chemical utilizationefficiency, and, on the other hand, the need to minimize purge-gasresidence and chemical removal times. One approach to overcome theinherent limitations of “pulsed” delivery of gaseous material is toprovide each reactant gas continuously and to move the substrate througha region containing each gas in succession. In these systems, somemechanism must be employed to confine a particular gas to a spatialregion in order that the substrate can sample all of the gases duringits movement, but the individual mutually reactive gases cannot mixcausing undesirable CVD deposition. Such systems can be referred to asspatially confined ALD systems. For example, U.S. Pat. No. 6,821,563entitled “GAS DISTRIBUTION SYSTEM FOR CYCLICAL LAYER DEPOSITION” toYudovsky, describes a processing chamber, under vacuum, having separategas ports for precursor and purge gases, alternating with vacuum pumpports between each gas port. Each gas port directs its stream of gasvertically downward toward a substrate. The separate gas flows areseparated by walls or partitions, with vacuum pumps for evacuating gason both sides of each gas stream. A lower portion of each partitionextends close to the substrate, for example, about 0.5 mm or greaterfrom the substrate surface. In this manner, the lower portions of thepartitions are separated from the substrate surface by a distancesufficient to allow the gas streams to flow around the lower portionstoward the vacuum ports after the gas streams react with the substratesurface.

A rotary turntable or other transport device is provided for holding oneor more substrate wafers. With this arrangement, the substrate isshuttled beneath the different gas streams, effecting ALD depositionthereby. In one embodiment, the substrate is moved in a linear paththrough a chamber, in which the substrate is passed back and forth anumber of times.

Another approach using continuous gas flow is shown in U.S. Pat. No.4,413,022 entitled “METHOD FOR PERFORMING GROWTH OF COMPOUND THIN FILMS”to Suntola et al. A gas flow array is provided with alternating sourcegas openings, carrier gas openings, and vacuum exhaust openings.Reciprocating motion of the substrate over the array effects ALDdeposition, again, without the need for pulsed operation. In theembodiment of FIGS. 13 and 14, in particular, sequential interactionsbetween a substrate surface and reactive vapors are made by areciprocating motion of the substrate over a fixed array of sourceopenings. Diffusion barriers are formed by having a carrier gas openingbetween exhaust openings. Suntola et al. state that operation with suchan embodiment is possible even at atmospheric pressure, although littleor no details of the process, or examples, are provided.

While systems such as those described in the '563 Yudovsky and '022Suntola et al. patents may avoid some of the difficulties inherent topulsed gas approaches, these systems have other drawbacks. Neither thegas flow delivery unit of the '563 Yudovsky patent nor the gas flowarray of the '022 Suntola et al. patent can be used in closer proximityto the substrate than about 0.5 mm. Neither of the gas flow deliveryapparatus disclosed in the '563 Yudovsky and '022 Suntola et al. patentsare arranged for possible use with a moving web surface, such as couldbe used as a flexible substrate for forming electronic circuits, lightsensors, or displays, for example. The complex arrangements of both thegas flow delivery unit of the '563 Yudovsky patent and the gas flowarray of the '022 Suntola et al. patent, each providing both gas flowand vacuum, make these solutions difficult to implement, costly toscale, and limit their potential usability to deposition applicationsonto a moving substrate of limited dimensions. Moreover, it would bevery difficult to maintain a uniform vacuum at different points in anarray and to maintain synchronous gas flow and vacuum at complementarypressures, thus compromising the uniformity of gas flux that is providedto the substrate surface.

US Patent Publication No. 2005/0084610 to Selitser discloses anatmospheric pressure atomic layer chemical vapor deposition process.Selitser states that extraordinary increases in reaction rates areobtained by changing the operating pressure to atmospheric pressure,which will involve orders of magnitude increase in the concentration ofreactants, with consequent enhancement of surface reactant rates. Theembodiments of Selitser involve separate chambers for each stage of theprocess, although FIG. 10 in 2005/0084610 shows an embodiment in whichchamber walls are removed. A series of separated injectors are spacedaround a rotating circular substrate holder track. Each injectorincorporates independently operated reactant, purging, and exhaust gasmanifolds and controls and acts as one complete mono-layer depositionand reactant purge cycle for each substrate as is passes there under inthe process. Little or no specific details of the gas injectors ormanifolds are described by Selitser, although it is stated that spacingof the injectors is selected so that cross-contamination from adjacentinjectors is prevented by purging gas flows and exhaust manifoldsincorporated in each injector.

Another approach for spatially confining gases in an ALD processingdevice is described in the above-cited U.S. patent application Ser. No.11/392,006 which discloses a transverse flow ALD device. In such adevice, various gases are directed parallel to each other and thus limitany gas intermixing by limiting the degree of countercurrent flow.

One of the most efficient methods for allowing for gas isolation is thefloating-head ALD device of the above-cited U.S. patent application Ser.No. 11/620,744. In this device, the pressure of flowing reactive andpurge gases is used as a means to separate the delivery head from thesubstrate. Due to the relatively large pressures that can be generatedin such a system, gases are forced to travel in well defined paths andthus eliminate undesired gas intermixing.

In the operation of a floating style ALD deposition head as proposedabove, it is very important to provide a method to allow robustdeposition of high quality thin films. In particular, it is importantthat the separation of the substrate from the deposition head bemaintained in such a way that potential mechanical and otherdisturbances do not lead to variations in coating quality.

OBJECT OF THE INVENTION

An object of the present invention is, when placing reactive gases inclose proximity in an ALD coating process, to deliver gases in arelatively precise way, with good uniformity over the dimensions of adelivery head.

Another object is to provide a means to maintain the substrate at afixed gap with respect to the delivery head, and to maintain this gapeffectively even in the presence of external disturbances.

Another object is to provide a means to use a floating style depositionhead in which the substrate can hang from the deposition head, with itsposition maintained by forces generated by flows and pressures set bythe delivery head and its operating regime.

Another object is to provide an ALD deposition method and apparatus thatcan be used with a continuous process and that can provide improved gasflow separation over earlier solutions.

Another object is to provide an ALD deposition method and apparatus thatis more robust to potential disturbances or irregularities in processconditions or circumstances during operation.

Another object is to provide, in embodiments that use a floatingdelivery head, an ALD deposition method and apparatus thatadvantageously provides improved mobility.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and process for depositing athin film material on a substrate, comprising simultaneously directing aseries of gas flows from the output face of a delivery head of a thinfilm deposition system toward the surface of a substrate, wherein theseries of gas flows comprises at least a first reactive gaseousmaterial, an inert purge gas, and a second reactive gaseous material.The first reactive gaseous material is capable of reacting with asubstrate surface treated with the second reactive gaseous material. Inparticular, the present invention relates to a delivery device forthin-film material deposition onto a substrate comprising:

-   -   (A) at least a first, a second, and a third source for at least        a first, a second, and a third gaseous materials;    -   (B) a substrate having a substrate surface and an average weight        per unit area;    -   (C) a deposition head for delivering the gaseous materials to        the substrate surface for thin film deposition comprising:        -   i) at least a first, a second, and a third inlet port for            receiving the first, the second, and the third gaseous            materials, respectively;        -   ii) at least one exhaust port for exhausting waste gases;        -   iii) an output face in proximity to the substrate surface            comprising a plurality of elongated openings, wherein            -   (a) each of the inlet ports is independently connected                to at least one (preferably a plurality of) first,                second, and third elongated output openings (each                associated or connected with an elongated emissive                channel) in the face of the deposition head for                supplying the respective gaseous materials to the                substrate; and            -   (b) the at least one exhaust port is connected to at                least two (preferably a plurality of) elongated exhaust                openings each having an associated pressure, wherein the                elongated exhaust openings (each associated or connected                with a corresponding elongated emissive channel) are                disposed such that at least a first, second, or third                elongated output opening is located between the at least                two (preferably each of the plurality of) exhaust                openings in the output face; and    -   wherein a substantially uniform distance between the output face        and the substrate surface is maintained at least in part by        pressure generated due to flows of one or more of the gaseous        materials from the elongated output openings to the substrate's        surface and wherein the difference between atmospheric pressure        and the average pressure of the elongated exhaust openings        measured in Pascals is at least two times the average weight per        unit area of the substrate, also measured in Pascals.

Preferably, the delivery head comprises a plurality of first elongatedemissive channels and/or a plurality of second elongated emissivechannels for various applications. However, as a minimum, a one-stagedelivery head can have, for example, only one metal and or one oxidizerchannel in combination with at least two purge channels. A plurality ofindividual “delivery-head sub-units” that are connected together, orthat treat the same substrate during a common period of time areconsidered a “delivery head” for the purpose of the present invention,even though separately constructed or separable after deposition.

In a preferred embodiment, the first and second gaseous materials can bemutually reactive gases, and the third gaseous material can be a purgegas such as nitrogen.

Another aspect of the present invention relates to a process fordepositing a thin film material on a substrate, comprisingsimultaneously directing a series of gas flows from the output face of adelivery head of a thin film deposition system toward the surface of asubstrate, and wherein the series of gas flows comprises at least afirst reactive gaseous material, an inert purge gas, and a secondreactive gaseous material, wherein the first reactive gaseous materialis capable of reacting with a substrate surface treated with the secondreactive gaseous material, wherein the delivery head comprises:

-   -   (a) at least a first, a second, and a third inlet port for        receiving the first reactive gaseous material, the second        reactive gaseous material, and the inert purge gas,        respectively;    -   (b) at least one exhaust port for exhausting waste gases;    -   (c) an output face in proximity to the substrate surface        comprising a plurality of elongated openings, wherein        -   (i) each of the inlet ports is independently connected,            respectively, to at least one first, second, and third            elongated output openings, each associated with an elongated            emissive channel, for supplying the respective gaseous            materials to the substrate; and        -   (ii) the at least one exhaust port is connected to at least            two elongated exhaust openings, each connected to or            associated with a corresponding elongated exhaust channel,            each elongated exhaust opening having an associated            pressure, wherein the elongated exhaust openings are            disposed such that at least a first, second, or third            elongated output opening is located between the at least two            elongated exhaust openings in the output face; and    -   wherein a substantially uniform distance between the output face        and the substrate's surface is maintained at least in part by        pressure generated due to flows of one or more of the gaseous        materials from the elongated output openings to the substrate's        surface and wherein the difference between atmospheric pressure        and the average pressure of the elongated exhaust openings        measured in Pascals is at least two times the average weight per        unit area of the substrate, also measured in Pascals.

In one preferred embodiment, all of the emissive gas flows in the outputface provide a pressure that substantially contributes to the separationof the surface of the substrate from the face of the delivery head,while a series of exhaust channels provide a suction force that preventsthe substrate from moving too far from the surface of the depositionhead.

In another preferred embodiment, the force of the exhaust channelsuction at the output face (i.e., at the exhaust openings) is largeenough to allow the substrate to be located below the deposition head,and that the suction provides the majority of the force required tocounteract gravity and prevent the substrate from falling.

In another embodiment, the system provides a relative oscillating motionbetween the distribution head and the substrate. In a preferredembodiment, the system can be operated with continuous movement of asubstrate being subjected to thin film deposition, wherein the system iscapable of conveying the support on or as a web past the distributionhead, preferably in an unsealed environment to ambient at substantiallyatmospheric pressure.

It is an advantage of the present invention that it can provide acompact apparatus for atomic layer deposition onto a substrate that iswell suited to a number of different types of substrates and depositionenvironments.

It is a further advantage of the present invention that it allowsoperation, in preferred embodiments, under atmospheric pressureconditions.

It is yet a further advantage of the present invention that it isadaptable for deposition on a web or other moving substrate, includingdeposition onto a large area substrate.

It is still a further advantage of the present invention that it can beemployed in low temperature processes at atmospheric pressures, whichmay be practiced in an unsealed environment, open to ambient atmosphere.The method of the present invention allows control of the gas residencetime τ in the relationship shown earlier in equation (3), allowingresidence time τ to be reduced, with system pressure and volumecontrolled by a single variable, the gas flow.

As used herein, the terms “vertical,” “horizontal,” “top,” “bottom,”“front,” “back,” or “parallel,” and the like, unless otherwiseindicated, are with reference to a front/bottom horizontal face of thedelivery device or a top horizontal parallel surface of the substratebeing treated, in an theoretical configuration in which the deliveryhead is vertically over the substrate, although that configuration isoptional, for example, the substrate can be positioned over the face ofthe delivery head or otherwise positioned.

These and other objects, features, and advantages of the presentinvention will become apparent to those skilled in the art upon areading of the following detailed description when taken in conjunctionwith the drawings wherein there is shown and described an illustrativeembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter of the present invention, itis believed that the invention will be better understood from thefollowing description when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a cross-sectional side view of one embodiment of a deliveryhead for atomic layer deposition according to the present invention;

FIG. 2 is a cross-sectional side view of one embodiment of a deliveryhead showing one exemplary arrangement of gaseous materials provided toa substrate that is subject to thin film deposition;

FIGS. 3A and 3B are cross-sectional side views of one embodiment of adelivery head, schematically showing the accompanying depositionoperation;

FIG. 4 is a perspective exploded view of a delivery head in a depositionsystem according including an optional diffuser unit;

FIG. 5A is a perspective view of a connection plate for the deliveryhead of FIG. 4;

FIG. 5B is a plan view of a gas chamber plate for the delivery head ofFIG. 4;

FIG. 5C is a plan view of a gas direction plate for the delivery head ofFIG. 4;

FIG. 5D is a plan view of a base plate for the delivery head of FIG. 4;

FIG. 6 is a perspective view showing a base plate on a delivery head inone embodiment;

FIG. 7 is an exploded view of a gas diffuser unit according to oneembodiment;

FIG. 8A is a plan view of a nozzle plate of the gas diffuser unit ofFIG. 7;

FIG. 8B is a plan view of a gas diffuser plate of the gas diffuser unitof FIG. 7;

FIG. 8C is a plan view of a face plate of the gas diffuser unit of FIG.7;

FIG. 8D is a perspective view of gas mixing within the gas diffuser unitof FIG. 7;

FIG. 8E is a perspective view of the gas ventilation path using the gasdiffuser unit of FIG. 7;

FIG. 9A is a perspective view of a portion of the delivery head in anembodiment using vertically oriented plates;

FIG. 9B is an exploded view of the components of the delivery head shownin FIG. 9A;

FIG. 9C is a plan view showing a delivery assembly formed using stackedplates;

FIGS. 10A and 10B are plan and perspective views, respectively, of aseparator plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 11A and 11B are plan and perspective views, respectively, of apurge plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 12A and 12B are plan and perspective views, respectively, of anexhaust plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 13A and 13B are plan and perspective views, respectively, of areactant plate used in the vertical plate embodiment of FIG. 9A;

FIG. 13C is a plan view of a reactant plate in an alternate orientation;

FIG. 14 is a side view of one embodiment of a deposition systemcomprising a floating delivery head and showing relevant distancedimensions and force directions;

FIG. 15 is a perspective view showing a distribution head used with asubstrate transport system;

FIG. 16 is a perspective view showing a deposition system using thedelivery head of the present invention;

FIG. 17 is a perspective view showing one embodiment of a depositionsystem applied to a moving web;

FIG. 18 is a perspective view showing another embodiment of depositionsystem applied to a moving web;

FIG. 19 is a cross-sectional side view of one embodiment of a deliveryhead with an output face having curvature;

FIG. 20 is a perspective view of an embodiment using a gas cushion toseparate the delivery head from the substrate;

FIG. 21 is a side view showing embodiment for a deposition systemcomprising a gas fluid bearing for use with a moving substrate; and

FIG. 22 is a magnification of the delivery head shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The present description is directed in particular to elements formingpart of, or cooperating more directly with, apparatus in accordance withthe invention. It is to be understood that elements not specificallyshown or described may take various forms well known to those skilled inthe art.

For the description that follows, the term “gas” or “gaseous material”is used in a broad sense to encompass any of a range of vaporized orgaseous elements, compounds, or materials. Other terms used herein, suchas: “reactant,” “precursor,” “vacuum,” and “inert gas,” for example, allhave their conventional meanings as would be well understood by thoseskilled in the materials deposition art. The figures provided are notdrawn to scale but are intended to show overall function and thestructural arrangement of some embodiments of the present invention.Terms “upstream” and “downstream” have their conventional meanings asrelates to the direction of gas flow.

The apparatus of the present invention offers a significant departurefrom conventional approaches to ALD, employing an improved distributiondevice for delivery of gaseous materials to a substrate surface,adaptable to deposition on larger and web-based or web-supportedsubstrates and capable of achieving a highly uniform thin-filmdeposition at improved throughput speeds. The apparatus and method ofthe present invention employs a continuous (as opposed to pulsed)gaseous material distribution. The apparatus of the present inventionallows operation at atmospheric or near-atmospheric pressures as well asunder vacuum and is capable of operating in an unsealed or open-airenvironment.

Referring to FIG. 1, there is shown a cross-sectional side view of oneembodiment of a delivery head 10 for atomic layer deposition onto asubstrate 20 according to the present invention. Delivery head 10 has agas inlet conduit or port 14 that serves as an inlet port for acceptinga first gaseous material, a gas inlet conduit or port 16 for an inletport that accepts a second gaseous material, and a gas inlet conduit orport 18 for an inlet port that accepts a third gaseous material. Thesegases are emitted at an output face 36 via elongated output openings orchannels 12, having a structural arrangement described subsequently. Thedashed-line arrows in FIG. 1 and subsequent FIGS. 2-3B refer to thedelivery of gases to substrate 20 from delivery head 10. In FIG. 1,arrows X also indicate paths for gas exhaust (shown directed upwards inthis figure) and exhaust openings or channels 22, in communication withan exhaust conduit or port 24 that provides an exhaust port. Forsimplicity of description, gas exhaust is not indicated in FIGS. 2-3B.Because the exhaust gases still may contain quantities of unreactedprecursors, it may be undesirable to allow an exhaust flow predominantlycontaining one reactive species to mix with one predominantly containinganother species. As such, it is recognized that the delivery head 10 maycontain several independent exhaust ports.

In one embodiment, gas inlet conduits 14 and 16 are adapted to acceptfirst and second gases that react sequentially on the substrate surfaceto effect ALD deposition, and gas inlet conduit 18 receives a purge gasthat is inert with respect to the first and second gases. Delivery head10 is spaced a distance D from substrate 20, which may be provided on asubstrate support, as described in more detail subsequently.Reciprocating motion can be provided between substrate 20 and deliveryhead 10, either by movement of substrate 20, by movement of deliveryhead 10, or by movement of both substrate 20 and delivery head 10. Inthe particular embodiment shown in FIG. 1, substrate 20 is moved by asubstrate support 96 across output face 36 in reciprocating fashion, asindicated by the arrow A and by phantom outlines to the right and leftof substrate 20 in FIG. 1. It should be noted that reciprocating motionis not always required for thin-film deposition using delivery head 10.Other types of relative motion between substrate 20 or delivery head 10could also be provided, such as movement of either substrate 20 ordelivery head 10 in one or more directions, as described in more detailsubsequently. In addition, if the deposition head contains enoughchannels or the desired coating is thin enough, the complete depositionmay be accomplished by a single unidirectional pass through the lengthof the coating system.

The cross-sectional view of FIG. 2 shows gas flows emitted over aportion of output face 36 of delivery head 10 (with the exhaust pathomitted as noted earlier). In this particular arrangement, eachelongated output opening or channel 12 is in gaseous flow communicationwith one of gas inlet conduits 14, 16 or 18 as shown in FIG. 1. Eachoutput channel 12 delivers typically a first reactant gaseous materialO, or a second reactant gaseous material M, or a third inert gaseousmaterial I.

FIG. 2 shows a relatively basic or simple arrangement of gases. It isenvisioned that a plurality of flows non-metal deposition precursors(like material O) or a plurality of flows metal-containing precursormaterials (like material M) may be delivered sequentially at variousports in a thin-film single deposition. Alternately, a mixture ofreactant gases, for example, a mixture of metal precursor materials or amixture of metal and non-metal precursors may be applied at a singleoutput channel when making complex thin film materials, for example,having alternate layers of metals or having lesser amounts of dopantsadmixed in a metal oxide material. Significantly, an inter-streamlabeled I for an inert gas, also termed a purge gas, separates anyreactant channels in which the gases are likely to react with eachother. First and second reactant gaseous materials O and M react witheach other to effect ALD deposition, but neither reactant gaseousmaterial O nor M reacts with inert gaseous material I. The nomenclatureused in FIG. 2 and following suggests some typical types of reactantgases. For example, first reactant gaseous material O could be anoxidizing gaseous material; second reactant gaseous material M would bea metal-containing compound, such as a material containing zinc. Inertgaseous material I could be nitrogen, argon, helium, or other gasescommonly used as purge gases in ALD systems. Inert gaseous material I isinert with respect to first or second reactant gaseous materials O andM. Reaction between first and second reactant gaseous materials wouldform a metal oxide or other binary compound, such as zinc oxide ZnO orZnS, used in semiconductors, in one embodiment. Reactions between morethan two reactant gaseous materials could form a ternary compound, forexample, ZnAlO.

The cross-sectional views of FIGS. 3A and 3B show, in simplifiedschematic form, the ALD coating operation performed as substrate 20passes along output face 36 of delivery head 10 when delivering reactantgaseous materials O and M. In FIG. 3A, the surface of substrate 20 firstreceives an oxidizing material continuously emitted from output channels12 designated as delivering first reactant gaseous material O. Thesurface of the substrate now contains a partially reacted form ofmaterial O, which is susceptible to reaction with material M. Then, assubstrate 20 passes into the path of the metal compound of secondreactant gaseous material M, the reaction with M takes place, forming ametallic oxide or some other thin film material that can be formed fromtwo reactant gaseous materials. Unlike conventional solutions, thedeposition sequence shown in FIGS. 3A and 3B is continuous duringdeposition for a given substrate or specified area thereof, rather thanpulsed. That is, materials O and M are continuously emitted as substrate20 passes across the surface of delivery head or, conversely, asdelivery head 10 passes along the surface of substrate 20.

As FIGS. 3A and 3B show, inert gaseous material I is provided inalternate output channels 12, between the flows of first and secondreactant gaseous materials O and M. Notably, as was shown in FIG. 1,there are exhaust channels 22, but preferably no vacuum channelsinterspersed between the output channels 12. Only exhaust channels 22,providing a small amount of draw, are needed to vent spent gases emittedfrom delivery head 10 and used in processing.

In one embodiment, as described in more detail in copending, commonlyassigned U.S. patent application Ser. No. 11/620,744, herebyincorporated by reference in its entirety, gas pressure is providedagainst substrate 20, such that separation distance D is maintained, atleast in part, by the force of pressure that is exerted. By maintainingsome amount of gas pressure between output face 36 and the surface ofsubstrate 20, the apparatus of the present invention provides at leastsome portion of an air bearing, or more properly a gas fluid bearing,for delivery head 10 itself or, alternately, for substrate 20. Thisarrangement helps to simplify the transport requirements for deliveryhead 10, as described subsequently. The effect of allowing the deliveryhead to approach the substrate such that it is supported by gaspressure, helps to provide isolation between the gas streams. Byallowing the head to float on these streams, pressure fields are set upin the reactive and purge flow areas that cause the gases to be directedfrom inlet to exhaust with little or no intermixing of other gasstreams. In such a device, the close proximity of the delivery head tothe substrate leads to relatively high pressure and high variations ofpressure under the head. The absence of a gas diffuser system or aninadequate gas diffusion system within the head would indicate thatthere is little pressure drop for gases flowing within the head. In sucha case, if random forces cause a small increase on the gap on one sideof the head, the pressure in that area may be lowered and gas may flowinto that area in too high a proportion. Thus, a gas diffuser isrequired so that gas flow out of the head is maintained relativelyuniformly despite potential variations under the delivery head.

In one embodiment, a delivery device having an output face for providinggaseous materials for thin-film material deposition onto a substratecomprises:

(a) a plurality of inlet ports comprising at least a first inlet port, asecond inlet port, and a third inlet port capable of receiving a commonsupply for a first gaseous material, a second gaseous material, and athird gaseous material, respectively; and

(b) at least three groups of elongated emissive channels, a first groupcomprising one or more first elongated emissive channels, a second groupcomprising one or more second elongated emissive channels, and a thirdgroup comprising at least two third elongated emissive channels, each ofthe first, second, and third elongated emissive channels allowinggaseous fluid communication with one of corresponding first inlet port,second inlet port, and third inlet port;

wherein each first elongated emissive channel is separated on at leastone elongated side thereof from the nearest second elongated emissivechannel by a third elongated emissive channel;

wherein each first elongated emissive channel and each second elongatedemissive channel is situated between third elongated emissive channels,

wherein each of the first, second, and third elongated emissive channelsextend in a length direction and are substantially in parallel;

wherein each of the elongated emissive channels in at least one group ofelongated emissive channels, of the three groups of elongated emissivechannels, is capable of directing a flow, respectively, of at least oneof the first gaseous material, second gaseous material, and the thirdgaseous material substantially orthogonally with respect to the outputface of the delivery device, which flow of gaseous material is capableof being provided, either directly or indirectly from each of theelongated emissive channels in the at least one group, substantiallyorthogonally to the surface of the substrate.

In one embodiment, at least a portion of the delivery device is formedas a plurality of apertured plates, superposed to define a network ofinterconnecting supply chambers and directing channels for routing eachof the first, second, and third gaseous materials from its correspondinginlet port to its corresponding elongated emissive channels.

For example, the first and second gaseous materials can be mutuallyreactive gases, and the third gaseous material can be a purge gas.

The exploded view of FIG. 4 shows, for a small portion of the overallassembly in one embodiment, how delivery head 10 can be constructed froma set of apertured plates and shows an exemplary gas flow path for justone portion of one of the gases. A connection plate 100 for the deliveryhead 10 has a series of input ports 104 for connection to gas suppliesthat are upstream of delivery head 10 and not shown in FIG. 4. Eachinput port 104 is in communication with a directing chamber 102 thatdirects the received gas downstream to a gas chamber plate 110. Gaschamber plate 110 has a supply chamber 112 that is in gas flowcommunication with an individual directing channel 122 on a gasdirection plate 120. From directing channel 122, the gas flow proceedsto a particular elongated exhaust channel 134 on a base plate 130. A gasdiffuser unit 140 provides diffusion and final delivery of the input gasat its output face 36. An exemplary gas flow F1 is traced through eachof the component assemblies of delivery head 10. The x-y-z axisorientation shown in FIG. 4 also applies for FIGS. 5A and 7 in thepresent application.

As shown in the example of FIG. 4, delivery assembly 150 of deliveryhead 10 is formed as an arrangement of superposed apertured plates:connection plate 100, gas chamber plate 110, gas direction plate 120,and base plate 130. These plates are disposed substantially in parallelto output face 36 in this “horizontal” embodiment. Gas diffuser unit 140can also be formed from superposed apertured plates, as is describedsubsequently. It can be appreciated that any of the plates shown in FIG.4 could itself be fabricated from a stack of superposed plates. Forexample, it may be advantageous to form connection plate 100 from fouror five stacked apertured plates that are suitably coupled together.This type of arrangement can be less complex than machining or moldingmethods for forming directing chambers 102 and input ports 104.

As indicated above, the delivery device for thin-film materialdeposition onto a substrate can preferably comprise a gas diffuser,wherein the gaseous material from at least one (preferably all three) ofa plurality of elongated channels of said first, second, and thirdelongated emissive channels is capable of passing through the gasdiffuser prior to delivery from the delivery device to the substrate,including deposition onto the substrate, wherein the delivery deviceallows the passage of each gaseous material in order through therespective inlet port, elongated emissive channels, and (with respect tosaid at least one plurality of emissive channels) gas diffuser. The gasdiffuser can be either in said at least one plurality of emissiveelongated channels and/or upstream of the emissive elongated channel.

In an advantageous embodiment, the gas diffuser is capable of providinga friction factor, to be described subsequently, that is greater than1×10², preferably 1×10⁴ to 1×10⁸, more preferably 1×10⁵ to 5×10⁶. Thisprovides back pressure and promotes the equalization of pressure wherethe flow of the at least one first, second and third gaseous materialexits the delivery device.

This friction factor assumes that the characteristic area in theequation below is equal to the entire area between exhaust elongatedchannels on either side of each emissive elongated channel of said atleast one plurality of emissive elongated channels. In other words, thearea is defined by a straight line connecting the two ends of therespective exhaust elongated channels. For the purpose of the apparatusclaims, this also assumes a representative gas that is nitrogen at 25°C. and an average velocity of between 0.01 and 0.5 m/sec, for thepurpose of calculating the friction factor for the apparatus apart froma method of use. The average velocity is calculated based on the flowrate divided by the characteristic area A defined below. (Theserepresentative values are for characterizing the delivery device apartfrom its method of use and do not apply to the process according to theinvention, in which actual values during the process apply.)

The term “friction factor” can be explained as follows. When a flow ofgas is passed through the channel, there will exist a higher pressure onthe upstream side of the diffuser than exists on the downstream side dueto the resistive nature of the diffuser. The difference in pressure isthe known as the pressure drop across the diffuser.

A gas diffuser or other means for providing back pressure in thedelivery head (which diffuser can be an apparatus, material, orcombination thereof) provides a resistance to flow in a channel, whilestill allowing fluid to pass uniformly. A gas diffuser means may beplaced at the end of a flow channel of some shape. In the absence of thegas diffuser, fluid may tend to leave the channel at any spot and maynot be constrained to leave as uniformly. With a gas diffuser present,fluid traveling up to the gas diffuser will find a strong resistancethere, and will travel by path of least resistance along all areas ofthe diffuser to exit more uniformly, which is desired for smoother, morerobust operation.

Since a desired property of the gas diffuser is its resistance to flow,it is convenient to characterize this resistance by accepted means inthe field of fluid dynamics (Transport Phenomena, R. B. Bird, W. E.Stewart, E. N Lightfoot, John Wiley & Sons, 1960, hereby incorporated byreference). Pressure drops across a diffuser can be characterized by thefriction factor, f, presented by the gas diffuser:

$\begin{matrix}{f = \frac{F_{k}}{A \times K}} & (4)\end{matrix}$

where F_(k) is the force exerted due to the fluid flow, ultimatelyrelated to the pressure drop, A is a characteristic area, and Krepresents the kinetic energy of the fluid flow. Diffusers can take manyshapes. For a typical system, as described for the present invention, Ais disposed perpendicular to the output flow and F_(k) is disposedparallel to the output flow. Thus, the term F_(k)/A can be taken as thepressure drop ΔP caused by the gas diffuser.

The kinetic energy term of the flow is:

$\begin{matrix}{K = {\frac{1}{2}\rho\left\langle v \right\rangle^{2}}} & (5)\end{matrix}$

where ρ is the gas density and <v> is the average velocity, equal to theflow rate of the gaseous material divided by the characteristic area A.(The density of nitrogen can be used for a first approximation for thegases actually used in the process, or as a representative gas forcharacterizing the delivery head apparatus.) Thus, the pressure drop dueto a gas diffuser can be reduced to:

$\begin{matrix}{{\Delta\; P} = {\frac{1}{2}f\;\rho\left\langle v \right\rangle^{2}}} & (6)\end{matrix}$

Equation (6) can be used to calculate the friction factor f, adimensionless number, since the other factors can be experimentaldetermined or measured, as shown in the examples below.

Materials or devices exhibiting higher friction factors present a higherresistance to gas flow. The friction factor for a given diffuser meanscan be measured by disposing the diffuser in some channel, andsimultaneously recording the pressure drop as well as the flow rate ofgas presented to the diffuser. From the flow rate of gas and knowledgeof the shape of the channel, the velocity <v> can be calculated, thusallowing calculation of the friction factor from the above equation. Thefriction factor for a given system is not perfectly constant, but hassome relatively weak dependence upon the flow rate. For practicalpurposes, it is only important that the friction factor be known at flowrates typical of use in a given system or method. With respect to adelivery head apparatus, apart from the method, the average velocity <v>can be taken as 0.01 to 0.5 m/sec as a representative number. (Theclaimed friction factor in the case of the apparatus should be met forall average velocities <v> in this representative range.)

In one embodiment, a suitable gas diffuser is capable of providing afriction factor for gas flow through the gas diffuser that is greaterthan 1×10², preferably 1×10⁴ to 1×10⁸, more preferably 1×10⁵ to 5×10⁶.This provides the desired back pressure and promotes the equalization ofpressure where the gas flow of the at least one first, second and thirdgaseous material (preferably all three gaseous materials) exits thedelivery device through the gas diffuser.

As indicated above, the characteristic area A for determining theaverage velocity <v> for Equation (6) is equal to the entire areabetween exhaust elongated channels on either side of each individualemissive elongated channel among the emissive elongated channels in flowcommunication with the gas diffuser. In other words, the area is definedby a straight line connected the two ends of the respective exhaustelongated channels. For the purpose of the apparatus claims, this alsoassumes a representative gas that is nitrogen at 25° C.

The skilled artisan can appreciate that typical random materials byitself will not provide the necessary friction factor. For example, astainless steel perforated screen even though representing fairly smallfeatures for typical machined or mechanically fabricated elements, mayoffer a friction factor that is too low to be adequate by itself for thepresent gas diffuser.

For the purpose of determining the friction factor, in most cases, agood approximation can be made by using the pressure into the deliveryhead, since the effect of the flow path leading to the gas diffuser willbe relatively small.

A gas diffuser means can be a mechanically formed apparatus thatprovides the necessary friction factor, for example, wherein theemissive elongated channels are designed to provide the first, second,and third gaseous material indirectly to the substrate after passingthrough a gas diffuser element comprising openings in a solid material.For example, the solid material can be steel and the openings formed bymolding, machining, the application of laser or lithography, or thelike.

Alternatively, a gas diffuser means can comprise a porous material.Instead of machining holes in a solid material, a porous material havingtiny pores can be used to create the desired backpressure. The resultinguniform distribution of inlet gas allows improved uniformity ofdeposition growth as well as, for certain embodiments, better floatationof a floating head. Porous materials are advantageous for providing arelatively simple unit that avoids difficulty machining of steel and thelike.

In the literature, porous materials have been used to create backpressure for air bearings, but such applications are not concerned aboutcross-flow (i.e., gas moving laterally). Thus, sintered aluminaparticles might be used to form a membrane for an air bearing. In thepreferred embodiment of the ALD system of the present invention,however, gases preferably flow substantially vertically from the outlet,with minimal or no inadvertent sideways motion that could allow gasmixing. Therefore porous materials with substantially vertical tubularopenings or pores to direct the gas flow are especially desirable andadvantageous.

Porous materials have also been for filters, where the object is to keepone component of a flow on one side, while allowing another component topass through. In contrast, in the present invention, moderate resistanceto the flow of the entire gaseous material is the objective. For thispurpose, two preferred classes of porous materials are as follows:

A first preferred class of porous materials comprises porous materialswith uniform, controlled diameter, columnar-type pore structure. In amembrane (or layer) made of such material, flow through the membrane issubstantially uni-directional, essentially without any cross-flowbetween pore channels. Alumina formed by anodization of highly purealuminum is well-known in the literature for its uniformity of porediameter (though the cross-sectional shape of the pores is notnecessarily round or regular), and such materials are commerciallyavailable at diameters of 0.02, 0.1, and 0.2 microns. The pores inANOPORE alumina, a commercially available alumina, are fairly dense,1.23×10⁹ pores/cm² (J Chem Phys, V. 96, p. 7789, 1992). However, a widevariety of pore diameters and interpore distance can be fabricated.Porous materials can also be formed of titanium oxides, zirconiumoxides, and tin oxides (Adv. Materials, V. 13, p. 180, 2001). Anothercommercially available material with columnar pores is a PolycarbonateTrack Etch (PCTE) membrane, made from a thin, microporous polycarbonatefilm material, known as NUCLEOPORE. Block copolymers can form similarconfigurations, with a wide range of tunability.

Thus, in a preferred embodiment, the gas diffuser comprises porousmaterial comprises an isolating, non-connecting pores structure in whichpores are substantially vertical to the surface, for example, anodicalumina.

In all these materials, the precise range of pore diameter and densityof pores (or pore volume) must be adjusted to achieve the appropriatefriction factor for the flow required. It is desirable to avoidreactivity of the diffusing membrane with the flowing gases. This islikely to be less of a potential issue, for example, for inorganicoxides than for organic-based materials.

Furthermore, the membrane must have some mechanical toughness. Theflowing gases will exert pressure on the membranes. The toughness couldbe achieved by a support membrane, so that the friction factor isgenerated by a layer with smaller pores coupled with a more robust layerwith larger pores.

In a second preferred class of porous materials, porous materials arefabricated such that the flow can be isotropic, i.e. moving sidewaysinside the membrane, as well as through the membrane. However, forpresent purposes, such an isotropically-flowing material is preferablyseparated by walls on non-porous material (for example, ribs) thatisolate gaseous material in each output channel from gaseous material inother output channels and prevent gaseous materials from interminglingin the gas diffuser or when leaving the gas diffuser or delivery head.For example, such porous materials can be sintered from small particles,either organic or inorganic. Sintering typically involves applying heatand/or pressure, preferably both, sufficient to bond the particles. Awide variety of such porous materials are available commercially, suchas porous glass (VYCOR has, for example, having a void volume of 28%)and porous ceramics. Alternatively, fibrous materials can be compressedto create a tight network to limit or resist the flow of gas.Alternatively, porous stainless steel can be formed by plasma coatingonto a subsequently removed substrate.

In one embodiment, for producing suitable backpressure while stillproviding relative isolation between gas channels, polymeric materialstreated in a way to generate useful pores can be employed, for example,TEFLON material that is treated to produce porosity (GoreTex, Inc.;Newark, Del.). In this case, the pores may not be interconnected. Also,the natural chemical inertness of such materials is advantageous.

Porous materials can comprise pores formed from the interstitial spacebetween particles, pores that are interconnected voids in a solidmaterial formed by a voiding agent or other means, or pores that areformed from micro-scale or nano-scale fibers. For example, the porousmaterial can be formed from the interstitial space between inorganic ororganic particles which is held together by sintering, either bypressure and/or heat, adhesive material, or other bonding means.Alternatively, the porous material can result from the processing of apolymer film to generate porosity.

In one embodiment, a gas diffuser means comprises a porous material thatcomprise pores that are less than 10,000 nm in average diameter,preferably 10 to 5000 nm, more preferably 50 to 5000 nm in averagediameter, as determined by mercury intrusion porosity measurement.

Various configurations of the porous material in a gas diffuser meansare possible. For example, the porous material can comprise one or morelayers of different porous materials or a layer of porous materialsupported by a porous or perforated sheet, which layers are optionallyseparated by spacer elements. Preferably, the porous material comprisesa layer that is 5 to 1000 micrometers thick, preferably 5 to 100micrometers thick, for example, about 60 μm. In one embodiment, theporous material can be in the form of at least one horizontally disposedlayer that covers the face of the delivery assembly and comprises thepart of the delivery device from which the gaseous materials exit theoutput face.

The porous material can form a continuous layer, optionally withpassages mechanically formed therein. For example, the porous layer ofthe gas diffuser can comprise mechanically formed openings or elongatedchannels for the relatively unimpeded flow of exhaust gaseous materialback through the delivery device. Alternatively, the layer of porousmaterial can be in the form of a substantially completely continuousplate in a stack of plates.

In still another embodiment, the porous material can be introduced orformed inside elongated emissive channels or other walled channels inthe flow path from the elongated emissive channels, for example by thebonding or sintering of particles introduced into the channels. Channelscan be at least partially filled by porous material. For example, adiffuser element or portion thereof can be formed from elongatedchannels in a steel plate in which particles are introduced and thensintered.

Thus, a gas diffuser means can be an assembly of elements in whichporous material is held in separate confined areas. For example, porousalumina material can be grown onto a previously machined piece ofaluminum so that the resulting porous structure has big openings forpurge channels and sheets of vertical pores for the supply gases.

FIGS. 5A through 5D show each of the major components that are combinedtogether to form delivery head 10 in the embodiment of FIG. 4. FIG. 5Ais a perspective view of connection plate 100, showing multipledirecting chambers 102 and inlet ports 104. FIG. 5B is a plan view ofgas chamber plate 110. A supply chamber 113 is used for purge or inertgas for delivery head 10 in one embodiment. A supply chamber 115provides mixing for a precursor gas (O) in one embodiment; an exhaustchamber 116 provides an exhaust path for this reactive gas. Similarly, asupply chamber 112 provides the other needed reactive gas, secondreactant gaseous material (M); an exhaust chamber 114 provides anexhaust path for this gas.

FIG. 5C is a plan view of gas direction plate 120 for delivery head 10in this embodiment. Multiple directing channels 122, providing a secondreactant gaseous material (M), are arranged in a pattern for connectingthe appropriate supply chamber 112 (not shown in this view) with baseplate 130. Corresponding exhaust directing channels 123 are positionednear directing channels 122. Directing channels 90 provide the firstreactant gaseous material (O) and have corresponding exhaust directingchannels 91. Directing channels 92 provide third inert gaseous material(I). Again, it must be emphasized that FIGS. 4 and 5A-5D show oneillustrative embodiment; numerous other embodiments are also possible.

FIG. 5D is a plan view of base plate 130 for delivery head 10. Baseplate 130 has multiple elongated emissive channels 132 interleaved withelongated exhaust channels 134. Thus, in this embodiment, there are atleast two elongated second emissive channels and each first elongatedemissive channel is separated on both elongated sides thereof from thenearest second elongated emissive channel by firstly an elongatedexhaust channel and secondly a third elongated emissive channel. Moreparticularly there is a plurality of second elongated emissive channelsand a plurality of first elongated emissive channels; wherein each firstelongated emissive channel is separated on both elongated sides thereoffrom the nearest second elongated emissive channel by firstly anelongated exhaust channel and secondly a third elongated emissivechannel; and wherein each second elongated emissive channel is separatedon both elongated sides thereof from the nearest first elongatedemissive channel by firstly an elongated exhaust channel and secondlythird elongated emissive channel. Obviously, the delivery device cannevertheless comprise a first or second elongated emissive channel ateach of two ends of the delivery head that does not have a second orfirst elongated emissive channel, respectively, on the side closest toan edge (the upper and lower edge in FIG. 5D) of the output face of thedelivery device.

FIG. 6 is a perspective view showing base plate 130 formed fromhorizontal plates and showing input ports 104. The perspective view ofFIG. 6 shows the external surface of base plate 130 as viewed from theoutput side and having elongated emissive channels 132 and elongatedexhaust channels 134. With reference to FIG. 4, the view of FIG. 6 istaken from the side that faces the direction of the substrate.

The exploded view of FIG. 7 shows the basic arrangement of componentsused to form one embodiment of a mechanical gas diffuser unit 140, asused in the embodiment of FIG. 4 and in other embodiments as describedsubsequently. These include a nozzle plate 142, a gas diffuser plate146, and a face plate 148. Nozzle plate 142 mounts against base plate130 and obtains its gas flows from elongated emissive channels 132. Inthe embodiment shown in FIG. 8A, first diffuser output passage 143 inthe form of nozzle holes provide the needed gaseous materials. Slots 180are provided in the exhaust path, as described subsequently.

A gas diffuser plate 146, shown in FIG. 8B, which diffuses incooperation with nozzle plate 142 and face plate 148 is mounted againstnozzle plate 142. The arrangement of the various passages on nozzleplate 142, gas diffuser plate 146, and face plate 148 are optimized toprovide the needed amount of diffusion for the gas flow and, at the sametime, to efficiently direct exhaust gases away from the surface area ofsubstrate 20. Slots 182 provide exhaust ports. In the embodiment shown,gas supply slots forming second diffuser output passage 147 and exhaustslots 182 alternate in gas diffuser plate 146.

A face plate 148, as shown in FIG. 8C, then faces substrate 20. Thirddiffuser passage 149 for providing gases and exhaust slots 184 againalternate with this embodiment.

FIG. 8D focuses on the gas delivery path through gas diffuser unit 140;FIG. 8E then shows the gas exhaust path in a corresponding manner.Referring to FIG. 8D there is shown, for a representative set of gasports, the overall arrangement used for thorough diffusion of thereactant gas for an output flow F2 in one embodiment. The gas from baseplate 130 (FIG. 4) is provided through first diffuser passage 143 onnozzle plate 142. The gas goes downstream to second diffuser passage 147on gas diffuser plate 146. As shown in FIG. 8D, there can be a verticaloffset (that is, using the horizontal plate arrangement shown in FIG. 7,vertical being normal with respect to the plane of the horizontalplates) between passages 143 and 147 in one embodiment, helping togenerate backpressure and thus facilitate a more uniform flow. The gasthen goes further downstream to third diffuser passage 149 on face plate148 to provide output channel 12 in the output face. The differentdiffuser passages 143, 147 and 149 may not only be spatially offset, butmay also have different geometries to contribute to intermolecularmixing and homogenous diffusion of the gaseous materials when flowingthrough the delivery head.

In the particular case of the arrangement of FIG. 8D, the majority ofthe backpressure is generated by the nozzle holes forming passage 143.If this gas is directed without the subsequent passages 147 and 149 tothe substrate, the high velocity of the gas coming out of the nozzleholes may cause non-uniformities. Thus passages 147 and 149 help toimprove uniformity of the gas flow. Alternatively, a coating device canoperate with only a nozzle based back-pressure generator, thuseliminating passages 147 and 149, at the expense of slight coatingnon-uniformities.

The nozzle holes in the nozzle plate 142 can be of any size suitable forback-pressure generation. These holes are preferably less than 200microns, more preferably less than 100 microns in diameter on average.Furthermore, the use of holes in the back-pressure generator isconvenient but not necessary. The back pressure can also be generated byother geometries such as a slit, as long as the size is chosen toprovide the desired back pressure.

FIG. 8E symbolically traces the exhaust path provided for venting gasesin a similar embodiment, where the downstream direction is opposite thatfor supplied gases. A flow F3 indicates the path of vented gases throughsequential third, second, and first exhaust slots 184, 182, and 180,respectively. Unlike the more circuitous mixing path of flow F2 for gassupply, the venting arrangement shown in FIG. 8E is intended for therapid movement of spent gases from the surface. Thus, flow F3 isrelatively direct, venting gases away from the substrate surface.

Thus, in the embodiment of FIG. 4, the gaseous material from each of theindividual elongated emissive channels among the first, second, andthird elongated emissive channels 132 is capable of separately passingthrough the gas diffuser unit 140 prior to delivery from the deliverydevice to the substrate, wherein the delivery device allows the passageof each gaseous material, in order, through the respective inlet port,elongated emissive channels, and gas diffuser unit 140. The gas diffuserunit in this embodiment is gas diffuser means for each of the threegaseous materials, although separate or isolated diffuser elements canbe used that do not form a common assembly. Diffuser elements can alsobe associated with, or placed in, the exhaust channels.

In this embodiment, also, the gas diffuser unit 140 is a unit isdesigned to be separable from the rest of the delivery head 10, thedelivery assembly 150, and substantially covers the final openings orflow passages for the first, second, and third gaseous material in thedelivery device prior to the gas diffuser element. Thus, the gasdiffuser unit 140 provides essentially the final flow path for thefirst, second and third gaseous material prior to delivery from theoutput face of the delivery device to the substrate. However, the gasdiffuser element can also be designed as an inseparable part of deliveryhead 10.

In particular, the gas diffuser unit 140 in the embodiment of FIG. 7comprises interconnected vertically overlying passages in threevertically arranged gas diffuser components (or plates), in combinationproviding a flow path for gaseous materials. The gas diffuser unit 140provides two substantially vertical flow paths separated by asubstantially horizontal flow path, wherein each substantially verticalflow path is provided by one or more passages extending in an elongateddirection in at two elements, and wherein each substantially horizontalflow path is in a thin space between parallel surface areas of twoparallel gas diffuser components. In this embodiment, the threesubstantially horizontally extending diffuser components aresubstantially flat stacked plates, and a relatively thin space isdefined by the thickness of a central gas diffuser component (the gasdiffuser plate 146) situated between adjacent parallel gas diffusercomponents, the nozzle plate 142 and the face plate 148. However, two ofthe plates in FIG. 7 can be replaced by a single plate, in which gasdiffuser plate 146 and face plate 148 are, for example, machined orotherwise formed into a single plate. In that case, a single element orplate of the gas diffuser can have a plurality of passages each ofwhich, in perpendicular cross-section of the plate thickness takenparallel to an associated elongated emissive channel, forms an elongatedpassage parallel to the surface of the plate open at one surface of theplate, which elongated passage is integrally connected near one endthereof to a narrow vertical passage leading to the other surface of theplate. In other words, a single element could combine second and thirddiffuser passages 147 and 149 of FIG. 8D into a single element or plate.

Thus, a gas diffuser unit in accordance with the present invention canbe a multilevel system comprising a series of at least two substantiallyhorizontally extending diffuser components with parallel surfaces facingeach other in an orthogonal direction with respect to the face of thedelivery device (for example, stacked plates). In general, inassociation with each elongated emissive channel of the first, second,and third emissive channels, the gas diffuser comprises verticallyoverlying or superposed passages, respectively, in the at least twovertically arranged gas-diffuser plates, in combination providing a flowpath for gaseous material that comprises two substantially vertical flowpaths separated by a substantially horizontal flow path, wherein eachsubstantially vertical flow path is provided by one or more passages, orpassage components, extending in an elongated direction and wherein eachsubstantially horizontal flow path is provided by a thin space betweenparallel surface areas in parallel plates, wherein vertical refers tothe orthogonal direction with respect to the output face of the deliverydevice. The phrase “component passages” refers to a component of apassage in an element that does not pass all the way through theelement, for example, the two component passages formed by combiningsecond and third diffuser passages 147 and 149 of FIG. 8D into a singleelement or plate.

In the particular embodiment of FIG. 7, the gas diffuser comprises threevertically overlying sets of passages, respectively, in three verticallyarranged gas-diffuser plates, wherein a relatively thin space is definedby the thickness of a central gas diffuser plate situated between twoparallel gas diffuser plates. Two of the three diffuser components, asequentially first and third diffuser component, each comprises passagesextending in an elongated direction for the passage of gaseous material,wherein passages in the first diffuser component is horizontally offset(in a direction perpendicular to the length of the elongated direction)with respect to corresponding (interconnected) passages in the thirddiffuser component. This offset (between the passages 143 and passages149) can be better seen in FIG. 8D.

Furthermore, a sequentially second gas diffuser component positionedbetween the first and third diffuser component comprises passages 147each in the form of an elongated center opening that is relativelybroader than the width of the passages in each of the first and thirdsecond diffuser component, such that the center opening is defined bytwo elongated sides and contains the interconnected passages of thefirst diffuser component and the third diffuser component, respectively,within its borders when viewed from above the gas diffuser looking down.Consequently, the gas diffuser unit 140 is capable of substantiallydeflecting the flow of the gaseous material passing there through.Preferably, the deflection is at an angle of 45 to 135 degrees,preferably about 90 degrees, such that orthogonal gas flow is changed toparallel gas flow with respect to the surface of the output face and/orsubstrate. Thus, the flow of the gaseous material can be substantiallyvertical through the passages in the first and third gas diffusercomponents and substantially horizontal in the second gas diffusercomponent.

In the embodiment of FIG. 7, each of a plurality of passages in thefirst gas diffuser component comprises a series of holes or perforationsextending along an elongated line, wherein the correspondinginterconnected passages in the third diffuser component is an elongatedrectangular slot, which is optionally not squared at the ends. (Thus,more than one passage in the first gas diffuser component can connectwith a single passage in a subsequent gas diffuser component.)

Alternatively, as indicated above, a gas diffuser can comprise a porousmaterial, wherein the delivery device is designed such that each of theindividual emissive elongated channels provide gaseous materialindirectly to the substrate after passing through the porous materialeither within each individual emissive elongated channel and/or upstreamof each of the emissive elongated channel. Porous materials typicallycomprise pores that are formed by a chemical transformation or presentin a naturally occurring porous material.

Referring back to FIG. 4, the combination of components shown asconnection plate 100, gas chamber plate 110, gas direction plate 120,and base plate 130 can be grouped to provide a delivery assembly 150.Alternate embodiments are possible for delivery assembly 150, includingone formed from vertical, rather than horizontal, apertured plates,using the coordinate arrangement and view of FIG. 4.

Apertured plates used for delivery head 10 could be formed and coupledtogether in a number of ways. Advantageously, apertured plates can beseparately fabricated, using known methods such as progressive die,molding, machining, or stamping. Combinations of apertured plates canvary widely from those shown in the embodiments of FIGS. 4 and 9A-9B,forming delivery head 10 with any number of plates, such as from 5 to100 plates. Stainless steel is used in one embodiment and isadvantageous for its resistance to chemicals and corrosion. Generally,apertured plates are metallic, although ceramic, glass, or other durablematerials may also be suitable for forming some or all of the aperturedplates, depending on the application and on the reactant gaseousmaterials that are used in the deposition process.

For assembly, apertured plates can be glued or coupled together usingmechanical fasteners, such as bolts, clamps, or screws. For sealing,apertured plates can be skin-coated with suitable adhesive or sealantmaterials, such as vacuum grease. Epoxy, such as a high-temperatureepoxy, can be used as an adhesive. Adhesive properties of melted polymermaterials such as polytetrafluoroethylene (PTFE) or TEFLON have alsobeen used to bond together superposed apertured plates for delivery head10. In one embodiment, a coating of PTFE is formed on each of theapertured plates used in delivery head 10. The plates are stacked(superposed) and compressed together while heat is applied near themelting point of the PTFE material (nominally 327° C.). The combinationof heat and pressure then forms delivery head 10 from the coatedapertured plates. The coating material acts both as an adhesive and as asealant. KAPTON and other polymer materials could alternately be used asinterstitial coating materials for adhesion.

As shown in FIGS. 4 and 9B, apertured plates must be assembled togetherin the proper sequence for forming the network of interconnecting supplychambers and directing channels that route gaseous materials to outputface 36. When assembled together, a fixture providing an arrangement ofalignment pins or similar features could be used, where the arrangementof orifices and slots in the apertured plates mate with these alignmentfeatures.

Referring to FIG. 9A, there is shown, from a bottom view (that is,viewed from the gas emission side) an alternate arrangement that can beused for delivery assembly 150 using a stack of vertically disposedplates or superposed apertured plates that are disposed perpendicularlywith respect to output face 36. For simplicity of explanation, theportion of delivery assembly 150 shown in the “vertical” embodiment ofFIG. 9A has two elongated emissive channels 152 and two elongatedexhaust channels 154. The vertical plates arrangement of FIGS. 9Athrough 13C can be readily expanded to provide a number of emissive andexhaust elongated channels. With apertured plates disposedperpendicularly with respect to the plane of output face 36, as in FIGS.9A and 9B, each elongated emissive channel 152 is formed by having sidewalls defined by separator plates, shown subsequently in more detail,with a reactant plate centered between them. Proper alignment ofapertures then provides fluid communication with the supply of gaseousmaterial.

The exploded view of FIG. 9B shows the arrangement of apertured platesused to form the small section of delivery assembly 150 that is shown inFIG. 9A. FIG. 9C is a plan view showing a delivery assembly 150 havingfive channels for emitted gases and formed using stacked aperturedplates. FIGS. 10A through 13B then show the various plates in both planand perspective views. For simplicity, letter designations are given toeach type of apertured plate: Separator S, Purge P, Reactant R, andExhaust E.

From left to right in FIG. 9B are separator plates 160 (S), also shownin FIGS. 10A and 10B, alternating between plates used for directing gastoward or away from the substrate. A purge plate 162 (P) is shown inFIGS. 11A and 11B. An exhaust plate 164 (E) is shown in FIGS. 12A and12B. A reactant plate 166 (R) is shown in FIGS. 13A and 13B. FIG. 13Cshows a reactant plate 166′ obtained by flipping the reactant plate 166of FIG. 13A horizontally; this alternate orientation can also be usedwith exhaust plate 164, as required. Apertures 168 in each of the platesalign when the plates are superposed, thus forming ducts to enable gasto be passed through delivery assembly 150 into elongated emissive 152and elongated exhaust channels 154, as were described with reference toFIG. 9A. (The term “superposed” or “superposition” has its conventionalmeaning, wherein elements are laid atop or against one another in suchmanner that parts of one element align with corresponding parts ofanother and that their perimeters generally coincide.)

Returning to FIG. 9B, only a portion of a delivery assembly 150 isshown. The plate structure of this portion can be represented using theletter abbreviations assigned earlier, that is:

S-P-S-E-S-R-S-E-S

(With the last separator plate in this sequence not shown in FIG. 9A or9B.) As this sequence shows, separator plates 160 (S) define eachchannel by forming side walls. A minimal delivery assembly 150 forproviding two reactive gases along with the necessary purge gases andexhaust channels for typical ALD deposition would be represented usingthe full abbreviation sequence:

S-P-S-E1-S-R1-S-E1-S-P-S-E2-S-R2-S-E2-S-P-S-E1-S-R1-S-E1-S-P-S-E2-S-R2-S-E2-S-P-S-E1-S-R1-S-E1-S-P-S

where R1 and R2 represent reactant plates 166 in different orientations,for the two different reactant gases used, and E1 and E2 correspondinglyrepresent exhaust plates 164 in different orientations.

Elongated exhaust channel 154 need not be a vacuum port, in theconventional sense, but may simply be provided to draw off the flow inits corresponding output channel 12, thus facilitating a uniform flowpattern within the channel. A negative draw, just slightly less than theopposite of the gas pressure at neighboring elongated emissive channels152, can help to facilitate an orderly flow. The negative draw can, forexample, operate with draw pressure at the source (for example, a vacuumpump) of between 0.2 and 1.0 atmosphere, whereas a typical vacuum is,for example, below 0.1 atmosphere.

Use of the flow pattern provided by delivery head 10 provides a numberof advantages over conventional approaches, such as those noted earlierin the background section, that pulse gases individually to a depositionchamber. Mobility of the deposition apparatus improves, and the deviceof the present invention is suited to high-volume depositionapplications in which the substrate dimensions exceed the size of thedeposition head. Flow dynamics are also improved over earlierapproaches.

The flow arrangement used in the present invention allows a very smalldistance D between delivery head 10 and substrate 20, as was shown inFIG. 1, preferably under 1 mm. Output face 36 can be positioned veryclosely, to within about 1 mil (approximately 0.025 mm) of the substratesurface. The close positioning is facilitated by the gas pressuregenerated by the reactant gas flows. By comparison, CVD apparatusrequires significantly larger separation distances. Earlier approachessuch as that described in the U.S. Pat. No. 6,821,563 to Yudovsky, citedearlier, were limited to 0.5 mm or greater distance to the substratesurface, whereas embodiments of the present invention can be practicedat less than 0.5 mm, for example, less than 0.450 mm. In fact,positioning the delivery head 10 closer to the substrate surface ispreferred in the present invention. In a particularly preferredembodiment, distance D from the surface of the substrate can be 0.20 mmor less, preferably less than 100 μm.

It is desirable that when a large number of plates are assembled in astacked-plate embodiment, the gas flow delivered to the substrate isuniform across all of the channels delivering a gas flow (I, M, or Omaterials). This can be accomplished by proper design of the aperturedplates, such as having restrictions in some part of the flow pattern foreach plate which are accurately machined to provide a reproduciblepressure drop for each emissive elongated output or exhaust channel. Inone embodiment, output openings or channels 12 exhibit substantiallyequivalent pressure along the length of the openings, to within no morethan about 10% deviation. Even higher tolerances could be provided, suchas allowing no more than about 5% or even as little as 2% deviation.

Although the method using stacked apertured plates is a particularlyuseful way of constructing a delivery head, there are a number of othermethods for building such structures that may be useful in alternateembodiments. For example, the apparatus may be constructed by directmachining of a metal block, or of several metal blocks adhered together.Furthermore, molding techniques involving internal mold features can beemployed, as will be understood by the skilled artisan. The apparatuscan also be constructed using any of a number of stereolithographytechniques.

In FIG. 14, a representative number of output channels 12 and exhaustchannels 22 are shown. The pressure of emitted gas from one or more ofoutput channels 12 generates a force, as indicated by the downward arrowin this figure, and optional spring 170 generates a force in theopposite direction to assist the fluid-bearing effect. In order for thisforce to provide a useful cushioning or “air” bearing (fluid gasbearing) effect for delivery head 10, there must be sufficient landingarea, that is, solid surface area along output face 36 that can bebrought into close contact with the substrate. The percentage of landingarea corresponds to the relative amount of solid area of output face 36that allows build-up of gas pressure beneath it. In simplest terms, thelanding area can be computed as the total area of output face 36 minusthe total surface area of output openings or channels 12 and exhaustopenings or channels 22. This means that total surface area, excludingthe gas flow areas of output channels 12, having a width w1, or ofexhaust channels 22, having a width w2, must be maximized as much aspossible. A landing area of 95% is provided in one embodiment. Otherembodiments may use smaller landing area values, such as 85% or 75%, forexample. Adjustment of gas flow rate could also be used in order toalter the separation or cushioning force and thus change distance Daccordingly.

It can be appreciated that there would be advantages to providing afluid gas bearing, so that delivery head 10 is substantially maintainedat a distance D above substrate 20. This would allow essentiallyfrictionless motion of delivery head 10 using any suitable type oftransport mechanism. Delivery head 10 could then be caused to “hover”above the surface of substrate 20 as it is channeled back and forth,sweeping across the surface of substrate 20 during materials deposition.

In one such embodiment, since the separation distance D is relativelysmall, even a small change in distance D (for example, even 100micrometers) would require a significant change in flow rates andconsequently gas pressure providing the separation distance D. Forexample, in one embodiment, doubling the separation distance D,involving a change less than 1 mm, would necessitate more than doubling,preferably more than quadrupling, the flow rate of the gases providingthe separation distance D. As a general principle, it is considered moreadvantageous in practice to minimize separation distance D and,consequently, to operate at reduced flow rates.

FIG. 22 shows a magnification of the delivery head (10) as depicted inFIG. 1, focusing on a single deposition segment including a supply oroutput channel 12 and an exhaust channel 22. Due to the symmetry of thedeposition head, analytical calculations to determine the approximatefloating behavior of the head can be performed by considering only acentral element of the head defined by the dotted lines (x10) whichextend to the middle of a set of the supply and exhaust openings. Thesubstrate 20 is maintained in a fixed gap with respect to the deliveryhead by a balance of the forces present in the system. The balance offorces comprises three elements. Forces will be defined as positive whenthey work to push the substrate into contact with the deposition head.

The first force results from the pressure of the coating gases, whichtends to push the substrate away for the head. This pressure iscontinuously varying along the length L, with a maximum pressure ofP_(in) caused by the supply gases and a minimum pressure P_(out) causedby draw, or suction, from the exhaust port. The resulting force on thesubstrate from this pressure is the average pressure (properlyintegrated) multiplied by the active area A of the segment defined bylines x10, which is L times the width W.

The second force results from the effect of atmospheric pressure,P_(atm), acting on the surface of the substrate that is not in contactwith the deposition head. This force is simply the atmospheric pressuretimes the area A. This force is always positive.

The third force F_(m) contains any additional mechanical forces thatexist in the system. These forces may result from gravity, or theapplication of any other mechanical, magnetic, or electrical forcescausing the substrate to change position relative to the depositionhead. The force in this case must be considered as the proportionalforce applied to the area segment A of the coating.

Under conditions where there is suction on the exhaust port, the valueof the exhaust area pressure P_(out) is set by experimental equipment.For the following calculations, the value of P_(out) is the value at theoutput face of the pressure in the immediate vicinity of the exhaustchannel. In most practical implementations of a delivery head of thisinvention, the exhaust pressure cannot be measured at the output facebut is instead measured by a pressure measuring means at a location atthe head exhaust port. Because the restriction of gas flow in a welldesigned delivery head occurs at the point of close contact of theoutput face with the substrate, there should be very low pressure dropdue to gas flow in the interior of the delivery head and therefore thepressure measured at the exhaust port should be very close to that atthe output face, and it is acceptable to consider that P_(out) isrepresented by the pressure measured at the exhaust port of the deliveryhead.

In a typical delivery head configuration there are many elongatedexhaust channels leading to fewer exhaust ports. There may be slightvariations in the actual pressures at the elongated exhaust channels onthe output face. It is sufficient for the purposes of this invention toassume that the P_(out) value can be represented by the average pressuretaken over all of the exhaust ports, which are connected to all of theelongated exhaust channels.

In order to approximate the pressures caused by the flow of coatinggases in the between the head and the substrate, the geometry can beconsidered as flow of gas through a narrow slit. The length of the slitis L, the thickness of the slit is 2 h, and the width of the slit is W.The volumetric flow Q through such a slit is defined as (Transportphenomena. Bird R B, Stewart W E & Lightfoot E N. New York: John Wileyand Sons, 1960. p. 62):

$\begin{matrix}{Q = {\frac{2}{3}\frac{\left( {P_{in} - P_{out}} \right)h^{3}W}{\mu\; L}}} & (7)\end{matrix}$

where μ is the viscosity of the gas.

The balance of forces described above would indicate that the stable gapbetween the substrate and delivery head is achieved when:P _(atm) A+F _(m) −P _(h) A=0  (8)

Equation (7) predicts that if the pressure were to be sampled along thelength L, it would have a linear profile. Therefore, the averagepressure produced by the coating gases, P_(h), is simply:

$\begin{matrix}{P_{h} = \left( \frac{P_{in} + P_{out}}{2} \right)} & (9)\end{matrix}$

Equations (8) and (9) can be substituted in equation (7) and rearrangedto yield a solution for half the slit (gap) thickness h as a function ofknown variables and parameters:

$\begin{matrix}{h = \sqrt[3]{\frac{3\; Q\;\mu\; L}{4\;{W\left( {P_{a\; t\; m} + \frac{F_{m}}{A} - P_{out}} \right)}}}} & (10)\end{matrix}$

To maintain the substrate at a fixed distance from the delivery head,and to control this distance robustly, it is desired that the floatinghead operate in a vacuum preload mode. In the vacuum preload mode, theabsolute pressure P_(out) is less than atmospheric pressure. In such acase, as long as the mechanical contribution F_(m)/A is small withrespect to the different between P_(atm) and P_(out), the substrate willbe forced into proximity with the delivery head in a way that it isstill levitated by gas pressure, but requires a forced to remove it fromthis position.

The critical point at which the substrate will no longer remain in closeproximity to the delivery head occurs when the term in the denominatorof Equation (10) reaches 0. The condition is met when:

$\begin{matrix}{\frac{F_{m}}{A} = {P_{out} - P_{a\; t\; m}}} & (11)\end{matrix}$

A significant contribution to F_(m) is from the weight of the substrateitself. The term F_(m)/A is:

$\begin{matrix}{\frac{F_{m}}{A} = {t \times \rho_{sub} \times g}} & (12)\end{matrix}$

where t is the substrate thickness, ρ_(sub) is the substrate density,and g is acceleration due to gravity. Assuming that thickness of typicalsubstrates can range from 100 microns to 2000 microns, and densities canrange from 1 to 10 kg/m3, the value of F_(m)/A will typically be in therange of 1 to 200 Pa.

In order for the system to be insensitive to mechanical perturbations,which will often relate to the weight of the substrate, it is desirablethat P_(atm)-P_(out) exceed F_(m)/A by a factor of 2 and preferably by afactor of 10.

A further benefit of operating in such a regime is that the substratecan hang from the delivery head.

Delivery head 10 may be positioned in some other orientation withrespect to substrate 20. For example, substrate 20 could be supported bythe fluid gas bearing effect, opposing gravity, so that substrate 20 canbe moved along delivery head 10 during deposition. One embodiment usingthe fluid gas bearing effect for deposition onto substrate 20, withsubstrate 20 cushioned above delivery head 10 is shown in FIG. 20.Movement of substrate 20 across output face 36 of delivery head 10 is ina direction along the double arrow as shown.

The alternate embodiment of FIG. 21 shows substrate 20 on a substratesupport 74, such as a web support or rollers, moving in direction Kbetween delivery head 10 and a gas fluid bearing 98. In this case, airor another inert gas alone can be used. In this embodiment, deliveryhead 10 has an air-bearing effect and cooperates with gas fluid bearing98 in order to maintain the desired distance D between output face 36and substrate 20. Gas fluid bearing 98 may direct pressure using a flowF4 of inert gas, or air, or some other gaseous material. It is notedthat, in the present deposition system, a substrate support or holdercan be in contact with the substrate during deposition, which substratesupport can be a means for conveying the substrate, for example aroller. Thus, thermal isolation of the substrate being treated is not arequirement of the present system.

As was particularly described with reference to FIGS. 3A and 3B,delivery head 10 requires movement relative to the surface of substrate20 in order to perform its deposition function. This relative movementcan be obtained in a number of ways, including movement of either orboth delivery head 10 and substrate 20, such as by movement of anapparatus that provides a substrate support. Movement can be oscillatingor reciprocating or could be continuous movement, depending on how manydeposition cycles are needed. Rotation of a substrate can also be used,particularly in a batch process, although continuous processes arepreferred. An actuator may be coupled to the body of the delivery head,such as mechanically connected. An alternating force, such as a changingmagnetic force field, could alternately be used.

Typically, ALD requires multiple deposition cycles, building up acontrolled film depth with each cycle. Using the nomenclature for typesof gaseous materials given earlier, a single cycle can, for example in asimple design, provide one application of first reactant gaseousmaterial O and one application of second reactant gaseous material M.

The distance between output channels for O and M reactant gaseousmaterials determines the needed distance for reciprocating movement tocomplete each cycle. For the example delivery head 10 of FIG. 4 may havea nominal channel width of 0.1 inches (2.54 mm) in width between areactant gas channel outlet and the adjacent purge channel outlet.Therefore, for the reciprocating motion (along the y axis as usedherein) to allow all areas of the same surface to see a full ALD cycle,a stroke of at least 0.4 inches (10.2 mm) would be required. For thisexample, an area of substrate 20 would be exposed to both first reactantgaseous material O and second reactant gaseous material M with movementover this distance. Alternatively, a delivery head can move much largerdistances for its stroke, even moving from one end of a substrate toanother. In this case the growing film may be exposed to ambientconditions during periods of its growth, causing no ill effects in manycircumstances of use. In some cases, consideration for uniformity mayrequire a measure of randomness to the amount of reciprocating motion ineach cycle, such as to reduce edge effects or build-up along theextremes of reciprocation travel.

A delivery head 10 may have only enough output channels 12 to provide asingle cycle. Alternately, delivery head 10 may have an arrangement ofmultiple cycles, enabling it to cover a larger deposition area orenabling its reciprocating motion over a distance that allows two ormore deposition cycles in one traversal of the reciprocating motiondistance.

For example, in one particular application, it was found that each O-Mcycle formed a layer of one atomic diameter over about ¼ of the treatedsurface. Thus, four cycles, in this case, are needed to form a uniformlayer of 1 atomic diameter over the treated surface. Similarly, to forma uniform layer of 10 atomic diameters in this case, then, 40 cycleswould be required.

An advantage of the reciprocating motion used for a delivery head 10 ofthe present invention is that it allows deposition onto a substrate 20whose area exceeds the area of output face 36. FIG. 15 showsschematically how this broader area coverage can be effected, usingreciprocating motion along the y axis as shown by arrow A and alsomovement orthogonal or transverse to the reciprocating motion, relativeto the x axis. Again, it must be emphasized that motion in either the xor y direction, as shown in FIG. 15, can be effected either by movementof delivery head 10, or by movement of substrate 20 provided with asubstrate support 74 that provides movement, or by movement of bothdelivery head 10 and substrate 20.

In FIG. 15 the relative motion directions of the delivery head and thesubstrate are perpendicular to each other. It is also possible to havethis relative motion in parallel. In this case, the relative motionneeds to have a nonzero frequency component that represents theoscillation and a zero frequency component that represents thedisplacement of the substrate. This combination can be achieved by: anoscillation combined with displacement of the delivery head over a fixedsubstrate; an oscillation combined with displacement of the substraterelative to a fixed substrate delivery head; or any combinations whereinthe oscillation and fixed motion are provided by movements of both thedelivery head and the substrate.

Advantageously, delivery head 10 can be fabricated at a smaller sizethan is possible for many types of deposition heads. For example, in oneembodiment, output channel 12 has width w1 of about 0.005 inches (0.127mm) and is extended in length to about 3 inches (75 mm).

In a preferred embodiment, ALD can be performed at or near atmosphericpressure and over a broad range of ambient and substrate temperatures,preferably at a temperature of under 300° C. Preferably, a relativelyclean environment is needed to minimize the likelihood of contamination;however, full “clean room” conditions or an inert gas-filled enclosurewould not be required for obtaining good performance when usingpreferred embodiments of the apparatus of the present invention.

FIG. 16 shows an Atomic Layer Deposition (ALD) system 60 having achamber 50 for providing a relatively well-controlled andcontaminant-free environment. Gas supplies 28 a, 28 b, and 28 c providethe first, second, and third gaseous materials to delivery head 10through supply lines 32. The optional use of flexible supply lines 32facilitates ease of movement of delivery head 10. For simplicity,optional vacuum vapor recovery apparatus and other support componentsare not shown in FIG. 16 but could also be used. A transport subsystem54 provides a substrate support that conveys substrate 20 along outputface 36 of delivery head 10, providing movement in the x direction,using the coordinate axis system employed in the present disclosure.Motion control, as well as overall control of valves and othersupporting components, can be provided by a control logic processor 56,such as a computer or dedicated microprocessor assembly, for example. Inthe arrangement of FIG. 16, control logic processor 56 controls anactuator 30 for providing reciprocating motion to delivery head 10 andalso controls a transport motor 52 of transport subsystem 54. Actuator30 can be any of a number of devices suitable for causing back-and-forthmotion of delivery head 10 along a moving substrate 20 (or, alternately,along a stationary substrate 20).

FIG. 17 shows an alternate embodiment of an Atomic Layer Deposition(ALD) system 70 for thin film deposition onto a web substrate 66 that isconveyed past delivery head 10 along a web conveyor 62 that acts as asubstrate support. The web itself may be the substrate being treated ormay provide support for a substrate, either another web or separatesubstrates, for example, wafers. A delivery head transport 64 conveysdelivery head 10 across the surface of web substrate 66 in a directiontransverse to the web travel direction. In one embodiment, delivery head10 is impelled back and forth across the surface of web substrate 66,with the full separation force provided by gas pressure. In anotherembodiment, delivery head transport 64 uses a lead screw or similarmechanism that traverses the width of web substrate 66. In anotherembodiment, multiple delivery heads 10 are used, at suitable positionsalong web conveyor 62.

FIG. 18 shows another Atomic Layer Deposition (ALD) system 70 in a webarrangement, using a stationary delivery head 10 in which the flowpatterns are oriented orthogonally to the configuration of FIG. 17. Inthis arrangement, motion of web conveyor 62 itself provides the movementneeded for ALD deposition. Reciprocating motion could also be used inthis environment. Referring to FIG. 19, an embodiment of a portion ofdelivery head 10 is shown in which output face 36 has an amount ofcurvature, which might be advantageous for some web coatingapplications. Convex or concave curvature could be provided.

In another embodiment that can be particularly useful for webfabrication, ALD system 70 can have multiple delivery heads 10, or dualdelivery heads 10, with one disposed on each side of web substrate 66. Aflexible delivery head 10 could alternately be provided. This wouldprovide a deposition apparatus that exhibits at least some conformanceto the deposition surface.

For the purposes of coating a flat substrate, it is generally assumedthat the output face of the deposition apparatus will also be flat.However, there are advantages to having an output face with a degree ofcurvature.

The curvature of a surface can generally be defined by a radius ofcurvature. The radius of curvature is the radius of a circle where asection of that circle matches the curvature of the output face. In thecase where the curvature of the surface varies and cannot be describedby a single radius, then the maximum curvature and the minimum radius ofcurvature may be used to define the characteristic radius of curvatureof the system.

For certain substrates it may be useful to have some curvature of thedeposition head in the direction of movement of the substrate. This canhave the beneficial effect of allowing the leading edge of the substrateto have lower downward force than the remaining portion of the substratesince curvature of the head will tend to pull the leading edge of thesubstrate away from the deposition output face.

For certain substrates it may be useful to have curvature in a directionthat is perpendicular to the direction of substrate motion. This degreeof curvature will have the effect of corrugation which is to increasethe rigidity of the substrate and perform a more robust coating.

The apparatus of the present invention is advantaged in its capabilityto perform deposition onto a substrate over a broad range oftemperatures, including room or near-room temperature in someembodiments. The apparatus of the present invention can operate in avacuum environment, but is particularly well suited for operation at ornear atmospheric pressure.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention as described above, and as noted in the appended claims, by aperson of ordinary skill in the art without departing from the scope ofthe invention. For example, while air bearing effects may be used to atleast partially separate delivery head 10 from the surface of substrate20, the apparatus of the present invention may alternately be used tolift or levitate substrate 20 from output surface 36 of delivery head10. Other types of substrate holder could alternately be used, includinga platen for example.

EXAMPLES

The theoretical deposition head used in all of the followingtheoretically calculated examples is composed of the followingarrangement of elongated slots:

-   -   P-Ex-O-Ex-P-Ex-M-Ex-P-Ex-O-Ex-P-Ex-M-Ex-P-Ex-O-Ex-P

Where P represents a purge channel, Ex represents an exhaust slot, Orepresents an oxidizer gas channel, and M represents a metal containinggas channel.

The elongated slots are separated on their long sides by 1.0 mm, andthey are 50 mm in length. The substrate for the purposes of the Examplesis chosen such that the substrate exactly covers the area generated bythe above arrangement, thus the substrate is 50 mm wide by 20 mm long.

Example 1 Comparative

This example quantifies the forces acting on a substrate when theaverage exhaust suction is ½ of the weight per unit area of thesubstrate.

In this example the substrate rests on top of the deposition head suchthat the force of gravity acts to pull the substrate toward thedeposition head.

The substrate is a piece of conventional glass with a density of 2.2g/cm³ and a thickness of 1 mm. Based upon its area the mass of the glasswill be 2.2 grams and the substrate weight, thus the gravitational forceacting on the substrate, will be 0.0216 N. The weight per unit area ofthe substrate is therefore 21.6 Pa.

If the exhaust channel pressure is set at 10.8 Pa (0.043 in H₂O) thenthe exhaust pressure will be ½ of the weight per unit area of thesubstrate. According to equation (5) the critical force at which thesubstrate will separate from the head will be 0.0108 N. Since this forceis substantially less than the weight of the substrate at 0.0216 N,small forces applied to the substrate are likely to significantly changethe substrate to delivery head gap leading to non-robust operation.

Example 2 Inventive

This example quantifies the forces acting on a substrate when theaverage exhaust suction is 5 times the weight per unit area of thesubstrate.

In this example the substrate rests on top of the deposition head suchthat the force of gravity acts to pull the substrate toward thedeposition head.

The substrate is a piece of conventional glass with a density of 2.2g/cm³ and a thickness of 1 mm. Based upon its area the mass of the glasswill be 2.2 grams and the substrate weight, thus the gravitational forceacting on the substrate, will be 0.0216 N. The weight per unit area ofthe substrate is therefore 21.6 Pa.

If the exhaust channel pressure is set at 108 Pa (0.43 in H₂O) then theexhaust pressure will be 5 times the weight per unit area of thesubstrate. According to equation (5) the critical force at which thesubstrate will separate from the head will be 0.108 N. Since this forceis substantially more than the weight of the substrate at 0.0216 N,small forces applied to the substrate are not likely to significantlychange the substrate to delivery head gap.

Example 3 Comparative

This example employs the same configuration as in Example 1 except thatthe deposition head is inverted with the substrate below the head.Therefore, the force of gravity acts to pull the substrate from thehead.

This example quantifies the forces acting on a substrate when theaverage exhaust suction is ½ of the weight per unit area of thesubstrate.

The substrate is a piece of conventional glass with a density of 2.2g/cm³ and a thickness of 1 mm. Based upon its area the mass of the glasswill be 2.2 grams and the substrate weight, thus the gravitational forceacting on the substrate, will be 0.0216 N. The weight per unit area ofthe substrate is therefore 21.6 Pa.

If the exhaust channel pressure is set at 10.8 Pa (0.043 in H₂O) thenthe exhaust pressure will be ½ of the weight per unit area of thesubstrate. According to equation (5) the critical force at which thesubstrate will separate from the head will be 0.0108 N. Since thegravitational force on the substrate is 0.0216 N, the force applied bythe deposition head will be insufficient to support the substrate andsubstrate will fall.

Example 4 Inventive

This example employs the same configuration as in Example 1 except thatthe deposition head is inverted with the substrate below the head.Therefore the force of gravity acts to pull the substrate from the head.

This example quantifies the forces acting on a substrate when theaverage exhaust suction is 5 times the weight per unit area of thesubstrate.

The substrate is a piece of conventional glass with a density of 2.2g/cm³ and a thickness of 1 mm. Based upon its area the mass of the glasswill be 2.2 grams and the substrate weight, thus the gravitational forceacting on the substrate, will be 0.0216 N. The weight per unit area ofthe substrate is therefore 21.6 Pa.

If the exhaust channel pressure is set at 108 Pa (0.043 in H₂O) then theexhaust pressure will be 5 times of the weight per unit area of thesubstrate. According to equation (5) the critical force at which thesubstrate will separate from the head will be 0.108 N. Since thegravitational force on the substrate is 0.0216 N, the force applied bythe deposition head will be sufficient to support the substrate andprevent it from falling.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention as described above, and as noted in the appended claims, by aperson of ordinary skill in the art without departing from the scope ofthe invention.

PARTS LIST

-   2_(h) thickness of slit-   10 delivery head-   12 output channel-   14, 16, 18 gas inlet conduit-   20 substrate-   22 exhaust channel-   24 exhaust conduit-   28 a, 28 b, 28 c gas supply-   30 actuator-   32 supply line-   36 output face-   50 chamber-   52 transport motor-   54 transport subsystem-   56 control logic processor-   60 Atomic Layer Deposition (ALD) system-   62 web conveyor-   64 delivery head transport-   66 web substrate-   70 Atomic Layer Deposition (ALD) system-   74 substrate support-   90 directing channel for precursor material-   91 exhaust directing channel-   92 directing channel for purge gas-   96 substrate support-   98 gas fluid bearing-   100 connection plate-   102 directing chamber-   104 input port-   110 gas chamber plate-   112, 113, 115, supply chamber-   114, 116 exhaust chamber-   120 gas direction plate-   122 directing channel for precursor material-   123 exhaust directing channel-   130 base plate-   132 elongated emissive channel-   134 elongated exhaust channel-   140 gas diffuser unit-   142 nozzle plate-   143, 147, 149 first, second, third diffuser passages-   146 gas diffuser plate-   148 face plate-   150 delivery assembly-   152 elongated emissive channel-   154 elongated exhaust channel-   160 separator plate-   162 purge plate-   164 exhaust plate-   166, 166′ reactant plate-   168 aperture-   170 spring-   180 sequential first exhaust slot-   182 sequential second exhaust slot-   184 sequential third exhaust slot-   A arrow-   D distance-   E Exhaust plate-   F1, F2, F3, F4 gas flow-   F_(m) mechanical force-   l third inert gaseous material-   L length-   K direction-   M second reactant gaseous material-   O first reactant gaseous material-   P purge plate-   P_(atm) atmospheric pressure-   P_(in) maximum pressure-   P_(out) minimum pressure-   R reactant plate-   S separator plate-   w1, w2 channel width-   X arrow-   x10 central element of delivery head 10

1. A process for depositing a thin film material on a substrate,comprising simultaneously directing a series of gas flows from an outputface of a delivery head of a thin film deposition system toward asubstrate surface, and wherein the series of gas flows comprises atleast a first reactive gaseous material, an inert purge gas, and asecond reactive gaseous material, wherein the first reactive gaseousmaterial is capable of reacting with the substrate surface treated withthe second reactive gaseous material, wherein the delivery headcomprises: (a) at least a first, a second, and a third inlet port forreceiving the first reactive gaseous material, the second reactivegaseous material, and the inert purge gas, respectively; (b) at leastone exhaust port for exhausting waste gases; (c) an output face inproximity to the substrate surface comprising a plurality of elongatedopenings; wherein: (i) each of the inlet ports is independentlyconnected, respectively, to at least one first, second, and thirdelongated output opening for supplying the respective gaseous materialsto the substrate; and (ii) the at least one exhaust port is connected toat least two elongated exhaust openings each having an associatedpressure, wherein the elongated exhaust openings are disposed such thatat least a first, a second, or a third elongated output opening islocated between the at least two elongated exhaust openings; and whereina substantially uniform distance between the output face and thesubstrate surface is maintained at least in part by pressure generateddue to flows of one or more of the gaseous materials from the elongatedoutput openings to the substrate surface and wherein the differencebetween atmospheric pressure and the average pressure of the elongatedexhaust openings measured in Pascals is at least two times the averageweight per unit area of the substrate, also measured in Pascals.
 2. Theprocess of claim 1 wherein flows of the first and second reactivegaseous materials are spatially separated substantially by at least theinert purge gas and an elongated exhaust opening.
 3. The process ofclaim 1 wherein the gas flows of the first reactive gaseous material,the second reactive gaseous material, and the inert purge gas incombination provides a pressure that substantially contributes toseparation of the surface of the substrate from the output face of thedelivery head.
 4. The process of claim 1 wherein gas flows are providedfrom a series of elongated output openings, substantially in parallel,positioned in close proximity to the substrate, with the output face ofthe delivery head spaced within 1 mm of the substrate surface subject todeposition.
 5. The process of claim 1 wherein a given area of thesubstrate is exposed to gas flow of the first reactive gaseous materialfor less than about 500 milliseconds at a time.
 6. The process of claim1 further comprising providing relative motion between the delivery headand the substrate.
 7. The process of claim 1 wherein the temperature ofthe substrate during deposition is under 300° C.
 8. The process of claim1 wherein the first reactive gas is a metal-containing reactive gaseousmaterial and the second reactive gas is a non-metallic reactive gaseousmaterial which react to form an oxide or sulfide material selected fromthe group consisting of tantalum pentoxide, aluminum oxide, titaniumoxide, niobium pentoxide, zirconium oxide, hafnium oxide, zinc oxide,lanthium oxide, yttrium oxide, cerium oxide, vanadium oxide, molybdenumoxide, manganese oxide, tin oxide, indium oxide, tungsten oxide, silicondioxide, zinc sulfide, strontium sulfide, calcium sulfide, lead sulfide,and mixtures thereof.
 9. The process of claim 1 wherein the process isused to make a semiconductor or dielectric thin film on a substrate, foruse in a transistor, wherein the thin film comprises a metal-oxide-basedmaterial, the process comprising forming on a substrate, at atemperature of 300° C. or less, at least one layer of ametal-oxide-based material, wherein the metal-oxide-based material isthe reaction product of at least two reactive gases, a first reactivegas comprising an organometallic precursor compound and a secondreactive gas comprising a reactive oxygen-containing gaseous material.10. The process of claim 1 wherein the average pressure of the exhaustchannels measured in Pascals is at least ten times the average weightper unit area of the substrate, also measured in Pascals.